Raised in Japan by American expatriates, Karen Leith now lives a reclusive life in New York, known chiefly for her highly regarded novels, of which the latest has won a major American literary award. When she is found on the floor behind her desk, surrounded by blood, it looks like foul play. But the only possible suspect is Leith's future daughter-in-law, Eva, who has recently become engaged. Eva swears by her innocence, even though she was the last to hear Leith alive and the first to find her dead.

Eva was waiting outside Leith's office to share the happy news and maintains that no one entered through that door, while the room's other possible exit was locked. The only one who can help her clear her name is mystery writer Ellery Queen, an acquaintance of the victim through New York's literary circles. Queen intends to unravel the locked-room mystery, but with no murder weapon and too many incriminating fingerprints, this case just might be one even he can't solve.